The present invention relates to a nozzle for spray tubes, and in particular, for spray tubes used in the paper and wood pulp industry to clean filters. Such spray nozzles are commonly utilized in a spray water system where the function of the nozzle is to form a spray jet from liquid contained in a spray tube and direct the spray against a filter cloth to be cleaned or flushed.
Usually, the spray water used to clean the filter cloth contains fibers and other particles, such as metal pieces, plastic pieces etc., since the spray water is recycled many times for cleaning the filter cloth. In order to prevent the nozzles from becoming clogged due to impurities in the spray water, expensive equipment can be installed to clean the water before it reaches the nozzles. This equipment may include spray water filters, bow sieves, or other means for removing unwanted debris from the water. However, in some cases no separate cleaning equipment is installed to clean the spray water before it reaches the spray nozzles and, as a result, the spray nozzles often need to be dismounted for cleaning.
Nozzle cloggings caused by impurities are often the result of some particle larger than the hole in the outlet of the nozzle creating a partial obstruction within the nozzle. When this happens, additional debris, will be unable to pass through the partial obstruction and will begin to form a plug. As spray water continues to pass through the nozzle, the plug grows far into the tube, upstream from the nozzle, until liquid no longer can pass.
In order to clean ordinary nozzles, a valve upstream from the nozzle must be closed and the nozzle must be dismounted before the plug can be removed. Finally, the valve is closed and the nozzle again is installed. The valve may then be reopened and the nozzle is operative. This known method involves interruptions in the operation of the cloth filter cleansing machine in which the nozzles are installed and is therefore an expensive aspect of the machine.
The present invention is designed to alleviate the problems caused by use of nozzles of the prior art and allows efficient and economical removal of debris from both the nozzle and spray tube.